Heat energy system



June 6, 1933. J. J. GREBE HEAT ENERGY SYSTEM OrginalfFled Jan. 26, 1927 2 Sheets-Sheet l INVENTOR. .7o/zzz .7. 57m? e.

BY @y June 6, 1933. J, J. GRE-:BE 1,912,938

HEAT ENERGY SYSTEM Original Fild Jan. `26, 1927 2 Sheets-Shee` 2 INVENTOR.

..7527 27 I ire/3@ A TTORNEYS gay/M? Patented June 6, 1933 U N I T E D vS ATE JOHN J'. GREBE, OF MIDLAND, MICHIGN', ASSIGNOR TO THE DOW CHEMICAL COMPANY,

` OF MIDLAND, MICHIGAN, A CORPORATION Oil MICHIGAN HEAT ENERGY SYSTEM Original application filed January 26, 1927, Serial No. 363,609. Divided and this application led February 2, 1929.

Steam at high temperature ran es oers advantages as a heat-energy agent ut practical limitations, until recently believed insuperable, have stood in the way of its use or application. The present invention has among its objects the provision of a cycle employing Suchagent and in a manner available for power purposes or in more general applications as may be desired, A further object is to provide a method of and apparatus for one pass generation of vapors at high pressure, without the difficulties and dangers heretofore attendant thereon. Other objects and advantages will appear as the description proceeds.

In my `co-pending application Serial No. 163,609, filed January 26, 1927, of which the present application is a division, I have set forth the power plant features of the present invention.

To the accomplishment of the foregoing and related ends, the invention, then, consists of the features hereinafter fully described, and particularly pointed out in the claims, the following description and the annexed drawings setting forth in detail but several of variousways in which the principle of the invention may be employed.

In said annexed drawings:

Fig. 1 shows in diagrammatic fashion one form of apparatus which may be used for carrying out the invention. Fig. 2 shows a modification of the heating portion of the apparatus shown in Fig. 1. Fig. 3 shows a method of heating the high-boiling point liquid with a separate heat source.

In its general aspects, the invention contemplatesemploying steam at high temperatures and providing a heat compensating or balancing system in transfer relation wherein any unvaporized liquid coming from the tubes exposed to furnace heat will be vaporized and may be superheated as desired. Such steam ma be used as an agent for high temperature eating, inA chemical work, or for other purposes, or it may be used for power generation. As an additional feature, the

steam may be reheated during and after use thus making further use more efficient.

Where operating at pressures over 1000 Serial No. 336,980.

pounds per square inch, it is Vvery desirable that the steam generator be cf tube type and may be a substantially continuous coil, without vapor or liquid drums. The pipe or pipes coming from the furnace containing fluid in partially or completely vaporized form is passed in heat exchange relation with a Huid having higher-boiling point in liquid state, said latter 4fluid operating `at low pressures. rlhis may take the form of an exchanger with separate passages for the partially or completely vaporized low-boiling point liquid and for the high-boiling point agent, or for instance, a coil for the partially or completely vaporized low-boiling point liquid passing through a drum containing thev high-boiling point agent either in liquid or vapor state or both. With the steam thus brought into relation with the higher-boiling point agent heated from the` furnace, if the temperature of the steam should exceed that of the high-boiling point agent, heat will be given up to the latter by the steam, but on the other hand when the temperature of the partially or completely vaporized liquid is below that of the highboiling point agent, as in normal condition, or in case of a sudden load increase on the steam system, the high-boiling point agent will supply heat to the steam. In this manner not only is a tendency to an equalization had at all times but the low pressure highboiling point agent acts to supply reserve capacity immediately available for the steam` system itself and without incurring the hazards incident to storage of a large body of liquid and vapor under very high pressure, or the expense contingent with large high pressure containers for vapor and fluid.

As high-boiling point substance or agent, I may emplo diphenyl oxide, or in some instances nap thalene, diphenyl, aluminum bromide, silicon bromide, tin bromide, mercury, phenanthrene, mineral oils, etc. or mixtures of these and others of like nature.

After using the steam yto give up heat in any apparatus desired, it may be broughty in heat transfer relation with the high-boiling point agent again, whereby the steam temperature is again raised to allow a more economical further use, and such procedure may be again repeated at laterA steps.

In Fig. 1 of the accompanying drawings, the reference character 1 designates a steam generator with tube or coil in a furnace 2 which may be heated by'suitable means, for.I4

i example, by powdered fuel supplied by feeder point of use for the steam ,here a turbine 10.

A jacket 1l about the turbine is heated by the vapor of the high-boiling point liquid coming k.from drum 5 by way of pipe 12. From the turbine 1() the steam exhausts through a pipe 13 to a reheater 14 which contains passages for the steam to a pipe 15l leading to another. turbine 10. Other passages in the reheater 14 receive the high-boiling point heating agent from the jacket 11 by a pipe 16 and thence forward it by a pipe 17 to the jacket 18 about the turbine 10. A dynamo 20 is illustrated as driven by the turbines.

From the turbine 10', a pipe 21 carries the exhaust steam to a reheater/22 and its passageways connect to outlet pipe 23 leading to a further turbine 24. A pipe 2 5 leads the high-boiling point agent from the jacket 18 to the compartments about the steam passageways in the reheater 22, anda pipe 26 hence leads to ajacket 27 about the steam pipe 23. A pump 28 returns the high-boiling point agent through pipes 29, 30 an'd 31 to the heater 7 in the furnace.

From the turbine 24, illustrated asdriving a dynamo 40, the steam. exhausts by a pipe 32 to a condenser 33, whence a pump 34 returns the condensate through pipe 35, feed heaters 36 and 37 to a preheater coil 38 and thence again to steam generator 1. An accumulator 3 9 may be connected in the condensate line, if desired.

In an equipment on this order, steam may be generated at any desired pressure and such equipment is particularly applicable for use with extremely high pressures limited only by the strength of the apparatus used, the hazards of operating at such pressures being greatly'minimized by my arrangement Vin that there is a relatively small body` of high pressure uid in existence at any given time. An ample heat reserve capacity is provided, however, as has been seen, in the body of high-boiling point agent, operating at low pressures, but which is in such heat relation with the steam system as to constitute a heat energy cycle therewith. Thus coming from thetubes exposed to furnace heat, as well as being an effective equalizer for maintaining a relatively uniform superheat for. the steam delivered for use. The number of reheat stages can be varied to suit conditions. The more such stages used, the greater the eiciency total in the system, the isothermal expansion then involving 'a series of steps in which thevtemperature may range between forillustration, say 725 and 650 F. For power plant purposes in some cases it will be suiiicient to apply the heat of the high-boiling point agent to the' jackets of 'the turbines only and omit the intermediate lreheaters. Or where preferred, the reheaters may be provided and the heating jackets may be omitted. All such details will of course necessarily vary with the particular kind of plant, the size of the plant, conditions of operation, etc., and any or all of the features of the invention may be applied, fas desired.

'Ihe Huid products of the-low-boiling point liquid, I have found, may be maintained at a relatively uniform degree of superheat by holding the vapor of the high-boiling point fluid at 'approximatel `a-uniform pressure. One preferred way o doing this is shown, wherein pipe 59 is connected to the high boilling point vapor line` 12, and leads to a uniform pressure valve 45 which maintains the high-boiling point fluid at uniform pressure by by-passing part or all of the vapor when its pressurel rises above a predetermined point. While the so by-passed -vapor can be utilized or condensed in any convenient manner, I prefer to pass it into a feed water heater 3,7 where it will give u its heat and when condensed will flow to t efeed pump for high-boiling point agent and be returned to the vaporizer. Operating in this 'manner has a further advantage in that it provides a convenient method of absorbing excess heat from the high-boiling point agent in the lowboiling point liquid, thus acting as an aid to the stabilization of the entire system.

Not only will the usual safety-valve precautions be applied on the steam line out of the boiler, but ordinarily it is also advisable to apply a large capacity safety-valve to the high-boiling point agent system, for instance a safety-valve 42 with connection 41 to the drum and on the other side to a cooling coil .the event of a break in the steam line within the drum 5, the contents, which in some instances might be of combustible characten pipe 51 connected to suitable heaters and feedA pump. The high-boiling point agent is vaporized in tubes 65 connecting headers 53 and 54, the vapor passing by means of pipe 55 to temperature balancer 48 Where it gives up part of its available heat to the iiuid products of the low-boilingpoint liquid. The vapor of the high-boiling point agent then passes out,of balancer 48 by means of pipe 61 to points of further use such as jacketing,

reheating, etc. When condensed, the liquid is returned to drum 53 by pipe 52 in any convenient manner. The bath of high-boiling point agent 48 is maintained at a relatively constant pressure and temperature by means of a uniform pressure valve 45 or like mechanism connected to main 61 by pipe 59. The vapor by-passed through valve 45 passes to points of usage or a condenser from whence it is returned to the vaporizer by meansof pipe 52. `A connection 56 is made between temperature balancer 48 and drum 53 to return condensed liquid to vaporizer 65. In some vcases it maybe desirable to lncrease the rate of circulation through vaporlzer 65 in which case a pump 57 may be used to advantage. The use of temperature balancer 48 with this type boiler equalizes the temperature between tubes and permits attaining a uniform degree of superheat, as desired.

Fig. 3 shows a modification of Fig. 2 wherein the high-boiling point agent 1s heated by any convenient means other than 1n contact with the same source of heat used to vaporlze the low-boiling point liquid. For example, a se arately fired furnace 62 may be4 used wfferein the high-boiling point agent 1n passing through suitable tubes 63 1s part1ally Vaporized and passes to temperature balancer 48 where it normally gives up part of its heat, as previously described. The vapor then passes out of temperature balancer 4 8 through pipe 61 to points of usage as prevlously described, from whence it is returned in condensed form by pipe 52 to container 68 for recycling. Liquid from temperature balancer 48 is then drawn through main 67 to container 68 by circulator 66 which forces same into tubes 63 for recycling. In some instances such vforced circulation has been found desirable since in general it increases the eiiiciency of heat absorption `and decreases the decomposition of the iiuid to a minimum. While only one method of heating the highboiling point agent has been described, it will be obvious to anyone versed in the art that many other methods of heating could be utilized Without departing from the spirit of my invention, for instance, by using oil, gas, a waste heat economizer, a condenser boiler, or the like.

One pass steam boilers operating at pressures below the critic-al pressure have heretofore been unsuccessful in large units due to the steam generating tubes becoming overheated, as is well known to the art. The Bensen boiler overcame this difficulty by generating steam at pressures at or above the critical pressure of water, thus keeping the tubes filled with a dense iiuid at all times which minimizes overheating and consequent damage. The steam so generated is then eX- panded to a useable lower pressure and reheated before use. This method, however, involves excessively thick tubes and high pressure equipment with consequent losses in heat transfer and compression energy at the boiler feed pumps. I have discovered, however, that high pressure steam can be successfully generated in a drumless boiler in combination with a suitable supplemental heater or temperature balancer of the type just described.

In order to avoid the diiiiculties of over heating and burning tubes, I allow the liquid being vaporized in generator 1, or as the case may be', to pass through the tubes exposed to direct heat, normally without reaching the stage of complete evaporation. The mixed vapor and liquid then pass to the supplemental heater or temperature balancer where the evaporation is completed by means of the heat of a high-boiling point agent in heat transfer relation. One of the principal advantages of producing high pressure steam in this manner is that the steam is generated at the useable pressure and by maintaining some liquid in the tubes exposed to direct heat, the danger of overheating and burning is avoided. y

In the operation of a'bi-fluid system of the type described., the boiling points of the two liquids should preferably be widely separated. Two such liquids, the use of which will be described, are Water and diphenyl oxide which have boiling points of 212 and 496 F., respectively. The diphenyl oxide may be safely held and boiled at 700 to 750 F. and a saturated water vapor temperature of 600 F. may then be chosen which corresponds to af'vapor pressure of 1500 pounds per sq. in. absolute. Diphenyl oxide at 700 F. will have a vapor pressure of 108 pounds per sq. in. absolute which at this temperature is not too high to permit the use of steel drums and standard well tried construction. These drums, due to the pressure being moderate,-can bemade large without-incurring inordinate construction charges, so that a relcient under normal conditions to evaporate all of the water supplied to the water boiler, the balance ofthe heat being supplied to the water in the tem erature balancingheat exchanger by the diphenyl oxide.

The ratio of heat transfer surfaces in the boiler itself' and in the heat exchanger may be so chosen that under normal operating con-` ditions the steam may be superheated, say, tol 650 F. or even to a temperature approximatin that of the di henyl oxide bath, thereby ma g it more e ective in a power generating cycle. In similar manner, these principles apply equally well when other high and low-boiling point liquids are concerned.

The relatively large amount of diphenyl oxide in the system maintained in active heat transfer relation with the water systempresents the advantages of heat storage incident to the use of the tube and drum type of water boiler heretofore employed for moderate pressures, constituting in effect an equivalent of the latter adapted to generate high pres` sure-high temperature steam without the hazards incident to maintaining a large body of fluid under such high pressure.

The heat required for a suddenly increased 4demandfor steam will be supplied from the A stored up heat in the diphenyl oxide by transfer in the heat exchanger. Conversely, a rise in superheat of steam, which would follow a suddenly decreased demand therefor, will be markedly reduced by transfer of heat from the superheated steam to the diphenyl oxide. Such actions follow upon the lag in the effect of furnace controls, actuated automatically or manually, in response to temperature or pressure changes in the steam systems following demand changes, since, owing to the large amount of diphenyl oxide employed, temperature and pressure changes therein will fol- .50 low slowly relative to similar changes in the small amount of water in the water system..

There is effected, consequently, an equahzing action between the two iuids tending to maintain pressure and temperature conditions ofsteam vapor more closely at the desired oints in the face of changing demands there or than is otherwise possible, the peaks and valleys representing severe fluctuations in pressure and temperature conditions of 40 the water vapor being flattened out by the heat inertia stabilizing eifectof the diphenyl oxide which in heat transfer relation thereto v may either supply to or take up heat from i5 There is, accldinglyma the'steam as conditions require. .b1 h h epossl e a 1g pressure vapor generator adapted to supply a vapor at substantially uniform pressure and temperature to meet varying and sud,-

.denly changing rates of demand, the limitations of flash type and one pass rapid evaporation systems being overcome by the use in heat exchange relation with the said vapor system of a relatively large body of a higher boiling point agent at higher temperature but il at lower pressure in a circulation type of tube and drum boiler, making the whole ensemble a safer y construction than thetive `iuid, Ido not wish to be limited to that fluid since I have found that in some instances other iuids may be employed, for instance, alcohol, acetone, Chlor-organic compounds, organic hydrocarbon compounds, inorganic compounds', etc.

Other modes of applying the principle of 'my invention may be employed, change being made in the details disclosed, provided the steps or means stated in any of the following claims, or the equivalent of such, be employed.

I therefore particularly point out and distinctly claim as my invention 1. In a one pass apparatus for generating relatively uniform pressure and temperature vapor from a low boiling point liquid exposed to a source of heat and then immedi-v ately to a temperature-balancing heat trans,- fer with a body of. hot heat-storing fluid of lower pressure, the combination including a drum for a temperature-balancing fluid, a heater lfor said fluid, inlet and outlet connections between said drum and heater, and a tubular duct for conducting a low boiling point'liquid in exposure to a source of heat and then immediately through said drum containing said temperature-balancing fluid and in indirect contact with a liquid portion thereof, said duct being proportioned so that normally a substantial proportion of the evaporation of the low boiling point liquid is done by heat absorbed from said body of temperature-balancing fluid. A,

2. In a method wherein steam is generated from water under pressure in tubes, in `one pass through a heating zone, the steps which comprise subjecting -such water in a portion of said pass to a source` of heat to normally produce a mixture of steam and water where in the steam predominates and the Water is present in substantial percentage, whereby the one pass tubes exposed to said source ofheat are protected from injury by over-heating, because of the presence therein of unvaporized liquid throughout the lengt-h thereof, subjecting such mixed fluid immediately to a temperature-balancing heat exchange with a body of a heat-storing fluid having a higher boiling point in liquid state than water under the same pressure, said higher boiling point agent being at least partially vaporized'and at a temperature suliciently high -to produce the desired working temperature for the steam, whereby the complete evaporation of the water is assured and variations in temperature incident to fluctuating steam demand are reduced.

3. In a method wherein steam is generated from water under pressure in tubes, in one pass through a heating zone, the steps which comprise subjecting such water in a portion of said pass to a source of heat to normally produce a mixture of steam and water wherein the steam predominates and the water is present in substantial percentage, whereby the one pass tubes exposed to said source of heat are protected from injury by over-heating,g because of the presence therein of unvaporized liquid throughout the length thereof, subjecting such mixed fluid immediately to a temperature-balancing heat exchange with a body of hot diphenyl oxide under moderate pressure,fsaid diphenyl oxide preferably being partially va orized and at a temperature approaching ut above the desired working temperature for the steam, whereby the complete evaporation of the water is assured and variations in temperature incident to fluctuating steam demand are reduced.

4. In a method of the character described, the steps which comprise passing a current of Water under pressure through a one pass heating zone wherein it' is converted into steam in two consecutive stages by heating it first with heat from burning fuel to normally produce steam having a substantial percentage of unvaporized water therein, and secondly with ,a body of hot products of a high boiling point heat-storing liquid obtained by heating same while controlling the temperature of the said products at a temperature level which lwill not only convert any water unvaporized in the first stage to steam but will continuously maintain the flow of said steam, thus produced, at approximately the desired temperature.

5J In a method of the character described involving the treating of a fluid which under normal conditions lof operation may vary in state from partially vaporized condition to superheated condition, the step which consists in bringing said fluid, converted at least in part from the liquid to the vaporized state and having a low. boiling point in liquid state, into ,a reversible heat-transfer relation witha liquid portion of a hot body of' heat-storing fluid, whereby the hot high boiling point agent acts by reversible heat-transfer with the low boiling point agent to re-l duce variations in temperature of the vapor of the low boiling point agent incident to fluctuating demands therefor.

6. In a method of the character described involving the treating of a fluid which under normal conditions of operation may vary in state from partially vaporized condition to superheated condition, the step which consists in bringing water, converted at least in part to the vaporized state, into reversible heat-transfer relation with a liquid portion of a heat-storing fluid having a higher boiling point in liquid state than water, said higher boiling point agent being at a proper temperature to reduce variations in steam temperature incident to fluctuating steam flow and to maintain approximately the desired working steam temperature.

7. In a method of the character described involving the treating of a fluid which under normal conditions of operation may vary in state from partially vaporized condition to superheated condition, the step which consists in bringing Water, converted at least in part to the vaporized state, into reversible heat-transfer relation with a liquid portion of a body of diphenyl oxide maintained at a moderate pressure and at a temperature approximating but above the desired-'working proper temperature for the steam, whereby the said hot diphenyl oxide acts by reversible heat-transfer with the steam to insure at least the complete generation thereof and to reduce Variations in steam temperature incident to fluctuating steam'flow.

8. In a method of producing super-heated steam in one pass at high pressure but substantially below the critical pressure there'- of, the steps which comprise heating said water to normally convert it at least in part to the 4vaporized state, and immediately subjecting the products of such step to a reversible heat-transfer with a body of diphenyl oxide maintained at a moderate pressure and at a temperature suciently high y to produce the desired working temperature for the steam, whereby the said hot diphenyl oxide acts in reversible heat-transfer with the steam to insure the complete, evaporation v at a, temperature suiciently high to produce the desired working temperature for the steam, whereby the said hot high boiling point agent acts in reversible heat transfer 5 with the steam to insure the complete evaporation of the water and to reduce variations in the superheat temperature of the steam incident to uctuating steam How.'

Signed by me this 30th day of January,

JOHN J. GREBE.

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